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Manholes can be made from the following materials:
• A36 mild (carbon) steel with these finishes:

Shop cleaned (SP3) and red-oxide primed. This is our standard finish.
Sandblasted to white metal (SP10) and primed with an inorganic zinc primer. Cathacoat 302 (also known as Devoe 302) is the primary inorganic zinc primer we use. This is a premium finish available at an additional cost.
Specialized paint / primer finishes are available at an additional cost. Custom paints may significantly increase the product price, since the paint systems cannot be re-used on other jobs.
Galvanizing is another premium finish available at an additional cost. This finish option also adds at least two weeks to the lead time.

• 304 Stainless Steel

• 316 Stainless Steel

Manhole cover thickness: (any material)
• 3/8” thick = ABS Grade

Deck ring dimensions:

• 3/4” thick = Steel, or Stainless Steel

• Standard width: 3”

Standard clear opening sizes:

• 15” x 23”

• 18” x 24”

Oval radius:

• Width of manhole clear opening divided by 2

• Example of measurements for 18” wide by 24” long hatch:

Take 18” / 2 = 9” radius for oval ends of hatch
Remaining straight section of hatch between curved ends of hatch cover = 24” - 9” - 9” = 6” straight section

Fasteners:

• Standard: plated studs, washers, and nuts

• Studs are threaded in to deck ring and plug welded

• Optional (for additional cost): stainless steel studs and washers, with brass or bronze nuts

Gaskets:

• 1/8” thick flat gasket with 20 holes

• Available in Neoprene or Buna-N

Optional features:

• Fold-down handle

• NPT plugs installed in cover

ABS Type Approval / Classing Agency Approval:

• All manholes are built to standards generally accepted by ABS, USCG, and other classing agencies. See link to ABS Explanation

• Manholes do NOT carry ABS “Type” approval. For further explanation, click here.

• Drawings and release letters are available for submission for classing agency review.

• It is the responsibility of the customer to verify which certification requirements (i.e. ABS, USCG, DNV, SOLAS) apply to their vessel, and to check with their local governing agency as to the requirements for certifications for all of the items quoted, based on the use for each item on the vessel, and the location of each item as installed on the vessel. Depending on the requirements of the governing agency, additional testing at the manufacturing plant may be required. A separate fee will be charged for any testing.

• Manholes conform to C-class fire rating - they are made of non-combustible materials, however, they are NOT designed or certified to resist the passage of fire from one space to another.

manhole #309

Semi-Flush Watertight and Oiltight Multibolt with Studs, Oval

For additional information download our pdfs and watch our videos

CEN-TEX spare parts